Abstracts Category : Other

Understanding of Oxide Based Resistive Random Access MemoryDevices with Multi-level Resistance States and Application

by Wenbo Chen

Non-volatile memory (NVM) are broadly used inremovable media storage, smart phones, solid-state drive, etc. andflash memory technology has been dominating NVM market for over 20years. However, further scaling of flash memory beyond sub 20 nmnode brings tremendous challenges in device performance. Forfurther scaling of Non-Volatile Memory technology beyond flashmemory devices, Resistive Random Access Memory (ReRAM) devices havebeen proposed as a promising candidate due to its superior deviceperformance and CMOS compatible process flow. This dissertationfocuses on three aspects of ReRAM research, multi-level cell (MLC)storage capacity, ReRAM crossbar array integration, and ReRAMpractical application. In MLC part, multi-step forming technologywas developed to substitute traditional one step forming in whichcurrent overshoot was suppressed and four stable resistance stateswere obtained. A comprehensive electrical characterization wasconducted and trade-offs among different states were studied. Inthe section detailing crossbar integration, switchable diode basedZnO ReRAM device was identified as one of the promising candidates.Ru/ZnO/TiN/W stack demonstrated forming-free, selfcompliance-current controlled, non-volatile, switchable diode typeReRAM characteristics in crossbar arrays which establishespotential application as high-density non-volatile memory. Finally,a complete voice cognitive system was built utilizing MLC ReRAMcrossbar array to demonstrate functionality at the simulationlevel. With these contributions, this work has established solidguidance for future ReRAM fabrication and characterization as wellas hardware system realization.Advisors/Committee Members: Jha, Rashmi (Committee Chair).